Energy management systems for monitoring and controlling the operation of electrical devices in conventional hydrocarbon powered vehicles are known in the art. Such systems may include(s) one or more device located near the particular electrical device to be monitored and controlled. These devices perform the desired monitoring or control functions in response to control signals provided by a central control unit or "brain". The central control unit is typically mounted at a location within the vehicle remote from the devices and is electrically connected to the device by a wiring harness. The control unit may include a processing system that processes any input signals received from the devices and transmits output signals to the devices to perform a specific control function. For example, the control unit can supply data to or even control a battery charger and be part of the charger itself. The processing system may be driven according to a specific control system program.
In conventional hydrocarbon powered vehicles, energy management is an ancillary feature that allows the vehicle's electrical functions, such as heating and cooling of the passenger compartment, to be performed in a more efficient or more comfortable manner. Such an energy management system may also operate to optimize the operation of the engine under particular conditions to improve engine efficiency or performance.
However, in electrically powered vehicles, energy management is not an ancillary feature but is a primary feature that is useful in monitoring and controlling the performance of the power source itself. In order to obtain maximum operating efficiency of an electrically powered vehicle, it is desired that the particular electric power source be controlled in such a manner to derive its maximum output capacity under a variety of different operating conditions. Accordingly, it is desired that the energy management systems is useful in electric powered vehicles, rather than monitor and control accessory electrical functions such as passenger compartment cooling and heating, operate primarily to monitor and control operating parameters of the power source itself, e.g., battery or battery cell voltage.
Energy management systems that are used with electrically powered vehicles to monitor and control the electric batteries, or individual cells in the batteries, used to power an electric vehicle, are known in the art. Such energy control systems are similar to those discussed above for use with hydrocarbon powered vehicles, in that such systems typically include one or more monitoring device and a central control unit. The monitoring devices are positioned near a particular battery or battery cell, and the central control unit is positioned within the vehicle at some remote location. Each monitoring device is connected to the central control unit by wired connection, typically by use of a wire harness, to facilitate transmission of information to and from the monitoring modules and the central control unit. The central control unit is configured to receive data from the monitoring devices, process the data, and produce control signals to the monitoring devices to effect a desired change in battery or battery cell operation.
In such systems, control signals are passed from the central control unit to a monitoring device, and information is passed from the monitoring devices to the central control unit through wires that run through the vehicle and connect each monitoring device with the central control unit. The wires can either be bundled together and routed along a primary wire harness for the vehicle's electrical system, or the wires may be routed separately from the primary wire harness.
A wire-type energy management system for monitoring and controlling operating parameters of an energy source in an electric powered vehicle is not desirable for a number of reasons. The use of wires, in addition to those already in the vehicle's electrical system, can add as much as fifty pounds to the weight of the vehicle. Such added weight can decrease the vehicle's acceleration and increase battery charge frequency. The use of a wire-type energy management system also increases the manufacturing cost of the vehicle, due both to the time associated with installing the additional wiring and the cost of the wire itself. The use of a wire-type energy management system also increases the cost of maintaining the system, because of the proximity of the wires connecting the monitoring devices to the batteries and resulting corrosion damage that is likely to occur. Such corrosion damage adversely effects the reliability and service life of a wire-type energy management system.
Additionally, the use of a wire-type energy management system requires use of high-voltage isolation components to reduce system interference or noise that may occur in signal wires from high-voltage wires that are typical of electric vehicle battery packs in the vehicle's electrical system. The use of such high-voltage isolation components both increases the manufacturing cost of the electric vehicle and increases vehicle weight. A wire-type energy management system is also limited in terms of future component upgrades, because of the need to provide additional wiring for each new upgraded component.
It is, therefore, desirable that an energy management system for use with an electric powered vehicle be constructed having multiple system devices capable of communicating with a central control unit in a wireless manner that does not add weight to the vehicle, is not vulnerable to battery corrosion, is easy and quick to install, does not require the use of high-voltage isolators, and that facilitates any upgrading or adding of new devices without modification. It is desirable that such an energy management system be configured having devices that are capable of being used to monitor and/or control one or more batteries or the battery cells of each such battery to perform control functions on such batteries to optimize battery performance, e.g., to provide battery equalization and/or battery thermal management, thereby optimizing the performance of a battery pack comprising such batteries. Particularly, it is desirable that the energy management system be configured to: (1) permit the detection of battery or battery cell changes; (2) enable storage of battery or battery cell performance information; (3) permit tracking battery or battery cell characteristics; and/or (4) permit control of a control device on a battery to optimize battery performance.